上部地壳的流体作用与大理岩的低温塑性   总被引：5，自引：0，他引：5  

刘俊来 Weber  K 《岩石学报》2000,16(4):499-505

本文应用光学显微镜、透射电子显微镜和阴极发光显微镜系统研究了Ｗａｔｅｒｂｅｒｇ断层带（纳米比亚）内粗晶大理岩中发育的构造岩,宏观碎裂结构与微观糜棱装结构是断层构造岩的主要特点。巨大的孪形碎屑与弥漫的细小粒质形成了鲜明的反差,广泛发育的压溶颖合线与多阶段方解石细脉遍布构造带不同部位,ＴＥＭ亚微粒粒度具有简单的峰值分布（～０．３～０．４μｍ）,但动态重结晶颗粒的粒度却具有较大的变化范围（０．１～３．０  相似文献   

Frost susceptibility of soils——A confusing concept that can misguide geotechnical design in cold regions     

DaiChao Sheng 《寒旱区科学》2021,13(2):87-94

Frost susceptibility is a concept widely used in cold region geotechnical design, to quantify the capacity of a soil in generating frost heave and frost damage. The laboratory test used to verify frost susceptibility of a soil is based on the measurement of frost heave generated in the soil under specific conditions. In reality this concept is, however, more related to the soil's potential to thaw weakening than to frost heave. Recent experimental studies show that frost non-susceptible soils like clean sand and clean gavel can also generate much ice segregation and frost heave if the conditions are favourable, hence challenging the usefulness and suitability of soil classification based on frost susceptibility. It is further shown that the concept is not suitable for design scenarios where frost heave itself is a serious hazard, such as in high-speed rail embankments.  相似文献   

洞庭湖流域气候变化特征(1961-2003年)   总被引：6，自引：0，他引：6  

王国杰  姜彤  王艳君  俞肇元 《湖泊科学》2006,18(5):470-475

以22个气象站1961-2003年的气象观测数据为基础,对洞庭湖流域的气温、降水和参照蒸散量进行趋势与突变分析．从1970年开始,洞庭湖流域经历了一个缓慢而稳定的增温过程,1990s发生突变进入快速增温时期;尤其是是在春、冬季节,这种突变式的增温特征非常显著;秋季持续而稳定增温,而夏季气温并无明显变化．进入1990s,洞庭湖流域降水有明显增多,尤其是夏季降水突变式增加;与此同时,夏季暴雨频率也突变式增大,但是暴雨强度并无明显变化．1900s迄今,参照蒸散量持续而稳定的减少,夏季减少量尤为显著．全球变暖的区域响应,驱动洞庭湖流域水循环速度加快,夏季降水增多,而蒸发能力减弱,这是1990s洞庭湖流域洪水频发的主要气候因子．  相似文献   

基于CRU资料的山西百年气温时空演变特征     

杜泽玉  曹富强  杨荣 《高原气象》2021,40(1):123-132

全球变暖的背景下,百年尺度上的区域气温变化规律,近年来已成为气候变化研究的热点.本文基于1901-2016年英国东英吉利(East Anglia)大学气候研究中心(Climatic Research Unit,CRU)提供的高分辨率、逐月气温数据集,采用一元线性回归法、滑动平均法和Mann-Kendall突变检验法分析...  相似文献   

Variation characteristics of evaporation in the Gulang River Basin during 1959-2013     

TingTing Wang  JianGuo Li  ZongXing Li 《寒旱区科学》2020,12(4):252-260

Based on monthly evaporation of two meteorological stations in the Gulang River Basin of China, the inter-annual variation of evaporation during 1959-2013 were analyzed using Mann-Kendall and wavelet analysis. The results demonstrated that the annual evaporation show a fluctuating increase over the past 50 years approximately, with an average increase rate of 4.26 mm per decade. The overall trend was decrease-increase-decrease. According to the cumulative anomaly curve,the turning point of the annual evaporation occurred in 1979, in which the evaporation increased in the early stage and decreased in the later stage. Meanwhile, the seasonal variation of the evaporation shows that it decreased in Spring and Autumn, and increased in Summer and Winter, especially obvious for the later. The evaporation abruptly changed in Spring and Summer in 2008 and in Winter in 1994. In addition, all evaporation increased after the changes. However,the evaporation in Autumn abruptly changed in 1986 and 1999, which show a trend of increase-decrease-increase.Wavelet analysis shows that evaporation in Summer and wet season would decrease in the next few years, and in the other seasons would increase. Based on the aforementioned analysis, it can be concluded that increased evaporation is mainly induced by increase of evaporation in dry season, especially in Winter, and this trend to be continued in the future for the Gulang River Basin.  相似文献   

温度骤降对大黄鱼Larimichthys crocea鱼卵与仔鱼的影响          下载免费PDF全文

周孔霖  杜萍  寿鹿  廖一波  刘永叶  黄伟 《海洋学研究》2018,36(4):68-75

滨海电厂温排水停止排放以及季节更替、寒潮来袭等现象会引起海水温度降低,从而对鱼类等变温生物产生冷冲击效应。本研究通过模拟水温骤降情形,以孵化率、死亡率、畸形率等为指标,探讨了温度骤降对大黄鱼早期发育阶段(鱼卵和仔鱼)的冷冲击作用。研究发现,大黄鱼仔鱼(3日龄)对温度骤降的敏感性略高于鱼卵。在大黄鱼鱼卵和仔鱼的适温范围内,当水温由22 ℃骤降至19 ℃或16 ℃时,鱼卵的孵化率和死亡率无明显变化,而胚胎发育和仔鱼的生长发育均减缓,仔鱼的死亡率提高;水温超出适温范围,由22 ℃骤降至13 ℃或10 ℃时,对鱼卵和仔鱼造成致命的冷冲击伤害,48 h累积死亡率分别为84.6%~100%和72.1%~98.2%。由此推测:当水温骤降超出适温范围后,大黄鱼的早期发育阶段遭受致命的冷冲击伤害,从而影响种群补充和年龄结构。  相似文献   

Abrupt uplift of Tibetan Plateau a t the end of early Pleistocene and Australasian impact event   总被引：2，自引：0，他引：2       下载免费PDF全文

REN Shoumai  L IU Yongjiang  GE Xiaohong 《世界地质(英文版)》2009,12(3):145-155

The latest sharp uplift of the Tibetan Plateau and adjacent mountains occurred at the end of the early Pleistocene. The uplift of the Plateau resulted from Late Mesozoic－Cenozoic comp ressional structure due to the subduction of the Indian Plate beneath the Asian continent. This event definitively effected the formation of basin-mountain relief, Cenozoic basin deformation, large scale aridity and desertification of western China. The Australasian meteorites impact event happened ca. 0.8 Ma ago, located in the triangle area of the Indian Ocean ridge (20°S/67°E) . The impact may have resulted in an acceleration of speeding of the Indian Ocean ridge pushing the Indian Plate to subduct rapidly northward. Thus, the impact event can give reasonable explanation for the dynamic background of the latest rapid uplift of the Tibetan Plateau and the continental deformation of western China and even of the Middle Asia.  相似文献   

Tracking climate change in Central Asia through temperature and precipitation extremes   总被引：1，自引：1，他引：0  

Zhang  Man  Chen  Yaning  Shen  Yanjun  Li  Baofu 《地理学报(英文版)》2019,29(1):3-28

Journal of Geographical Sciences - Under the impacts of climate change and human activities, great uncertainties still exist in the response of climate extremes, especially in Central Asia (CA). In...  相似文献   

Study on transmission mechanism of thermal infrared remote sensing for abrupt geothermal anomaly in volcanic region   总被引：2，自引：0，他引：2  

薄立群  华仁葵  徐新良  周德民 《中国地理科学(英文版)》1999,9(3):258-264

Ｇｅｏｔｈｅｒｍａｌａｎｏｍａｌｙｉｓａｐｈｅｎｏｍｅｎｏｎｔｈａｔｕｎｄｅｒｇｒｏｕｎｄｔｅｍｐｅｒａｔｕｒｅａｎｄｇｅｏｔｈｅｒｍａｌｇｒａｄｉｅｎｔｉｎｃｒｅａｓｅｓｍｕｃｈｍｏｒｅｉｎｔｈｅａｒｅａｔｈａｎｉｔｓｓｕｒｒｏｕｎｄｉｎｇｓ（Ｘｉａ,１９７９）．Ａｂｒｕｐｔｇｅｏｔｈｅｒｍａｌａｎｏｍａｌｙｍｅａｎｓｔｈａｔｕｎｄｅｒｇｒｏｕｎｄｔｅｍｐｅｒａｔｕｒｅｏｎｓｏｍｅｓｐｏｔｓａｓｗｅｌｌａｓｔｈｅａｆｆｅｃｔｅｄｔｅｍｐｅｒａｔｕｒｅｏｆｓｕｒｒｏｕｎｄｉｎｇａｒｅａａｂｒ…  相似文献   

青藏高原近40年来的降水变化特征   总被引：28，自引：7，他引：21  

张磊  缪启龙 《干旱区地理》2007,30(2):240-246

利用我国青藏高原地区的1961-2000年56个气象站的逐月降水资料,通过计算降水量的距平百分率,分析了青藏高原自1961至2000年以来降水量变化的趋势和1961-2000年以来各季降水量变化趋势,发现:青藏高原近40年来降水量呈增加趋势,降水量的线性增长率约为1.12mm/a。再将高原划分为四个季节,分析了各季40年来的降水量的变化情况得出:春季降水量年际变化较大,秋季降水量变化不明显。夏季降水量值较大而降水变化幅度较小,冬季降水量变化则与夏季相反。通过将青藏高原分为南北两个地区,分析了两个区的年降水量和四个季节的降水量的变化得出:高原南区1961-2000年降水量呈增加的趋势,降水量的线增长率为1.97 mm/a,春季和冬季降水量年际变化较大,夏季降水量变化不明显,秋季降水量略有增加;北区年降水量和夏季的降水量变化较小,秋季降水量的年际变化较大,冬季降水量变化最大。对青藏高原的南北两区用Mann-Kendall方法进行突变分析,显示高原南区分别在1978年和1994年发生突变,北区没有发现突变。  相似文献